Recommended standardized protocols for evaluating synthetic biomaterials, include the use of several in vitro cytotoxicity cell cultures tests. These tests indicate only a positive or negative response of the cultured cells to the test material, and do not address questions regarding material-cellular interactions. Animal studies are informative, however, the task of obtaining information on material-cellular interaction in vivo is difficult. The need for improved in vitro cell culture testing techniques has been indicated by several researchers. In this investigation, a new in vitro test system will be developed. This new test system will provide the means to better address issues concerning material-cellular interaction and elucidate common and fundamental factors of biocompatibility. This new test system will involve combining electrochemical corrosion analyses with suspension cell culture techniques, and thus allow for simultaneously monitoring and controlling corrosion processes, and evaluating cellular responses. The development of the suspension cell culture corrosion test system will be divided over two years. The first year will involve the construction of the electrochemical corrosion test system in the suspension cell culture, and evaluating the corrosion behavior of the test materials. The second year will test the new system by evaluating the generation and release of corrosion products from a series of nickel-chrome dental casting alloys and. their effect on cellular activity. New information will be obtained on the material-cellular interaction, and an improved understanding of biocompatibility achieved. This test system is unique in that the capability of conducting corrosion experiments within a cell culture system has not been attempted and will thus represent a step forward in improving cell culture test systems for the evaluation of dental biomaterials. Many questions remain concerning the interactions of dental materials with the host tissues, and these questions will be addressed at the NIH Technology Assessment Conference on Effects and Side Effects of Dental Restorative Materials. The development of this test system will allow for the investigation of some of these questions.